Plug fuse



March 31', 1936. H, wHlTE 2,036,008

PLUG FUSE Filed NOV. '7, 1934 INVENTOR MARTIN HENRY WHITE W ATTORNEY Patented Mar. 31, 1936 UNI-TED STATES PATENT OFFICE 5 Claims.

This invention relates to new and useful improvements in a plug fuse.

The invention has for an object the construction of a plug fuse which is characterized by a body consisting of a head section of transparent material and a foot section, and including a fuse element arranged within a compartment in the head section so as to be viewable through the head end thereof,

More particularly, the invention contemplates arranging the head section with a bulged portion acting as a magnifying glass so that the fuse element may be seen with greater ease.

Another object of the invention is to arrange the head section and the foot section to prevent twisting of the connecting wires.

Another one of the objects of this invention is the arrangement of a neon glow lamp in the compartment of the head section and beneath the fuse element, and arranged in a circuit and associated with a circuit of the fust element in such a manner that when the fuse blows the neon lamp will light and call attention to the fact. Further, because of the location of the lamp and fuse element, when the lamp is illuminated, the fuse element may readily be seen ruptured.

Still further, the invention also contemplates an arrangement wherein the foot section of the body is composed of a stationary part and a movable part, and mechanism associated with the movable part in such a manner that the fuse element may be taken out of the circuit to permit testing of the lamp.

Another object of this invention is the construction of a device as mentioned which is simple and durable, and which can be manufactured and sold at a reasonable cost.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawing forming a material part of this disclosure:-

Fig. 1 is a vertical sectional view of a plug fuse constructed according to this invention.

Fig. 2 is a horizontal sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is another horizontal sectional view but taken on the line 3-3 of Fig. 1.

Fig. 4 is another horizontal sectional view, taken on the line 4-4 of Fig. 1.

Fig. 5 is a perspective view, showing some of the parts used in this invention.

Fig. 6 is a fragmentary sectional view similar 5 to a portion of Fig. 1 but illustrating a modified construction.

Fig. 7 is a horizontal sectional view taken on the line 'I! of Fig. 6.

The plug fuse, according to this invention, in- 0 cludes a body comprising a head section ID of transparent material, and a foot section II. A threaded Contact shell 12 of standard design is mounted upon the body and serves to hold the sections together in a unit. More particularly, 15 a portion of the head section is formed with threads engaged by the threads of the shell, and the outer end of the shell is formed with an inturned flange engaging over an edge portion of the foot section. An end contact I 3 is mounted upon the foot end of the body and a flange or bead I3 is formed at its upper face.

, A recess in flange I3 is being engaged by a lug II of the foot portion H to prevent the end contact from rotation.

A fuse element I4 is arranged within the compartment IS in said body, and is viewable through the head of the body. A neon glow lamp I6 is also disposed in the compartment l5 and arranged beneath the fuse element M. A resistance I! of the grid leak type is disposed within the body as hereinafter further described.

The head section 10, preferably is made from glass material and at the top end is formed with a bulged portion Ill acting as a magnifying glass so that the fuse element I 4 may be seen with greater detail. The compartment [5 extends into a location immediately below the magnifying portion lfl The fuse element 14 is arranged with a reduced fusible portion [4 immediately beneath the magnifying portion Ill The body 10 is also formed with a top flange l0 by which the fuse may be readily gripped when screwed into a standard socket.

The foot portion 1 l is formed with a small projection l8 engaging into receiving opening in the head section so as to hold the parts against possible rotation and thus to prevent twisting of the connecting wires. The foot portion H is also provided with a cylindrical portion ll which extends into the compartment l5. This cylindrical portion may be filled with cement I 9 into which the bottom of the lamp I6 is engaged so that the lamp is firmly fixed in position. The lamp I6 is also held firmly by the wire connections and the locking arrangement of the invention. The lamp It includes a pair of spaced electrodes which are firmly held in position with a supporting bead 2| of glass within the bulb of the lamp which is supported by wires 20 and 20 The electrodes 20 are so located as to produce the maximum amount of signalling visibility which is accentuated by the bulged portion II] of head section II] and thus magnifying the rays of light when the neon glow lamp is in operation. Wires 20 and 20 extend from each of the electrodes out from the bottom end of the lamp.

The cylindrical portion Il may also be left without cement filling, if desired.

includes the resistance H, the lamp I6, and a wire 20 electrically connected with the shell 12. There is another circuit also extending from the end contact I3 to the shell contact I2 and includes a-fusible element I4 commencing at 14', passing through an opening II in the side of the cylindrical portion I I and extending up between the outer wall of the. cylindrical portion and the wall of the compartment I5. The circuit continues downward between the face of the compartment I5 and the outer face of the cylindrical portion II and ends at I4.

The cylindrical portion II is formed with an opening I I through which the lead 20' from the terminal of the lamp extends with the extremity HI of fuse member I4, and both continue through an opening II] in head section ID into a longitudinal slot lt The wire 20 and fuse extremity I l are soldered at I2 to the shell contact l2.

In Figs. 6 and 7 a modified form of the invention has been disclosed wherein provision is made for the testing of the lamp when desired. More particularly, the device has a foot section I I' consisting of a stationary part M and a movable part I I A control contact 23 is connected with the end contact I3 by wire M and mounted upon.

the movable part II and is adapted to engage a control contact 23 mounted upon a stationary portion of the body in a certain position of the movable part. A pin I8 projects from the part II into opening I8 in a stationary part of the body so as to prevent motion of part IN. A set screw engages through the stationary part I I and into the movable part II to hold these parts fixed together against disengaging movement, The set screw 25 may be partially removed from the moveable part II so as to engage a peripheral groove I I and to permit the movement of the last said part from the contacting position described, to a position in which contacts 23 and 23 are disengaged. The control contacts 23 and 23 are arranged in series in the fuse element circuit.

The operation of the device is as follows: The fuse element I4 may easily be examined when the plug fuse is out of a conventional socket, because of the enlarging qualities of the magnifying glass portion. When the plug fuse is used, it is engaged into a receiving socket in conventional fashion. The glow lamp will not be illuminated because of internal resistance and resistance I1, the current passing through the circuit which includes the fuse element M. In the event that the load through the fuse element is too great, it will burn and fuse and so break one of the circuits for the current. The current will therefore take the circuit through the glow lamp which will then be- There is an electric circuit from the end con- Y tact If to the shell contact I2, and this circuit 7 come illuminated. It is then an easy matter to detect that the fuse has blown.

Respecting the modified form shown in Figs. 6 and 7, with the contacts 23 and 23 engaged, the operation of the device is identical to that previously described. A feature of the construction is that the glow lamp may be tested by turning the movable part I I so as to break the circuit through the fuse element at the contacts 23 and 23 When the plug fuse is then engaged in the socket, the lamp will glow if it is in proper operating condition. After the test, the movable part I I? should be returned to close the circuit at the contacts 23 and 23 While I have illustrated and described the preferred embodiment of my invention, it is to be understood that l do not limit myself to the precise construction herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is:

1. In a plug fuse, a body consisting of a head section of transparent material and a foot section, a fuse element within a compartment in said body and viewable through the head end of the body, a neon glow lamp in said compartment and beneath said fuse element, an electric circuit for connection from an end contact of said body to a shell cont-act of said body and including a resistance and said lamp in series, another electric circuit from the end contact to the shell contact and. including said fuse element in series, a cylindrical portion from the. foot section engaging into the said compartment, and cement within the cylindrical portion for holding the lamp in a fixed position, said cylindrical portion having an outside diameter of smaller size than the compartment to produce a space between these parts, and said circuits, including wires passing through said space.

2. A plug fuse, comprising a body consisting of a head section of transparent material and a movable foot section, a threaded contact shell mounted on said body, an end contact on the foot end of said body, a fuse element within a compartment in said body and viewable through the head end of the body, a neon glow lamp in said compartment and beneath said fuse element, a resistance in said body, a control contact on the movable section and engageable with a control contact on the stationary portion of the body in a certain position of said movable section, an electric circuit from the 'end contact to the shell contact and including said resistant and lamp in series, and another electric circuit from the end contact to the shell contact and including the fuse element and the control contacts in series when the control contacts engage each other.

7 3. A plug fuse, comprising a body consisting of a head section of transparent material and a movable foot section, a threaded contact shell mounted on said body, an end contact on the foot end of said body, a fuse element within a compartment in said body and viewable through the head end of the body, a neon glow lamp in said compartment and beneath said fuse element, a resistance in said body, a control contact on the movable section and engageable with a control contact on the stationary portion of the body in a certain position of said movable section, an electric circuit from the end contact to the shell contact and including said resistant and lamp in series, and

another electric circuit from the end contact to the shell contact and including the fuse element and the control contacts in series when the control contacts engage each other, means for limiting the motion of the movable section.

4. A plug fuse, comprising a body consisting of a head section of transparent material and a movable foot section, a threaded contact shell mounted on said body, an end contact on the foot end of said body, a fuse element within a compartment in said body and viewable through the head end of the body, a neon glow lamp in said compartment and beneath said fuse element, a resistance in said body, a control contact on the movable section and engageable with a control contact on the stationary portion of the body in a certain position of said movable section, an electric circuit from the end contact to the shell contact and including said resistant and lamp in series, and another electric circuit from the end contact to the shell contact and including the fuse element and the control contacts in series when the control contacts engage each other, and means for holding the movable section against complete displacement.

5. In a plug fuse, a body consisting of a transparent head section with a recess extended in from the bottom thereof and a foot section with a cylindrical portion extending into said recess and having its outer face spaced from the side wall of the recess, a glow lamp supported within and on said cylindrical portion, and a fuse element having a central portion over said glow lamp and side portions continuing therefrom extending through the space between the wall of the recess of the cylindrical portion and supported on the cylindrical portion.

MARTIN HENRY WHITE. 

